Knitting method



1942- c. R. HUMPHREYS 2,301,703

KNITTING METHOD Filed Feb. 21, 1942 INVENTORV ATTORNEY Patented Nov. 10,1942 KNITTING METHOD Charles R. Bnmphreys, Chestertown, Md., assignorto, E. I. du Pont de Nemonra & Company, Wilmington, DeL, a corporationof Delaware Application February 21, 1942, Serial No. 431.851

40laims.

This invention relates to a method and apparatus for the knitting ofyarns, threads and filaments. The invention is particularly applicableto the knitting of nylon yarn on flat knitting apparatus for theproduction of full-fashioned hosiery fabric. The invention will, there-.fore, be described with particular reference to the knitting offull-fashioned hosiery fabric from nylon yarn.

The term, nylon, is used herein to designate the synthetic linearpolyamides of the general types disclosed in Carothers U. S. PatentsNos. 2,130,948 and 2,071,253.

In the flat knitting of nylon yarns into fullfashioned hosiery fabric,it is customary to use a light yarn, such as one of 30 denier, and onehaving a high degree of twist, such as 30 turns per inch. In the earlyexperiments, it was found that nylon yarn could not satisfactorily bemade into, stockings since the flat fabric had an extremely pronouncedtendency to edge-rolling,

with the result that the step of seaming became so complicated that theoperating labor became unbearably expensive. Moreover, it was found thatthe knitted fabric, as it was handled in the several operations, waslikely to be damaged by These problems were finally solved by sizing theyarn with specially prepared sizes. It was then found, however, that thestep of knitting itself became extremely critical because the sizingcomposition, momentarily softened by the usual moistening devicespreceding the knitting step proper, tended to soften and accumulate onthe needles and sinkers and tended to clog the fine moving parts of theknitting machine with the result that the machine had to be stopped forcleaning or that knitted fabric of faulty construction was prepared.This new problem has been partially solved by careful adjustment of theaction of the size composition in the knitting step at some cost ofprotection against edgeroliing and It is an object of the presentinvention to provide a improved method for the knitting of yarns,particularly the flat knitting of nylon yarns, which process will avoidclog in and gumming' of knitting machine elements, and will alsosubstantially prevent snaggi g and/or edgerolling.

Other objects of the invention will appear r. The objects of theinvention may be accompiished, in general. by knitting a dry yarn conbedefinitely softened by water, and then, after the knit goods has passedfrom the actual knitting mechanism, that is, the mechanism comprisingthe needles and sinkers, but before the fabric has proceeded far fromthe knittin mechanism, applying water to the knit goods whereby tosoften the size contained thereon and cause the yarn in the fabric toadjust itself to the knitted loops, and immediately thereafter dryingthe fabric to resolidify the size so as to protect the fabric againstsnagging and edgerolling. When it is stated that the yarn is knitted inits dry state, it does not mean that the yarn need be bone-dry but atequilibrium with the moisture in the atmosphere. yarn contains up to 10%moisture under ordinary room atmospheric conditions.

The invention will be more readily understood by reference to thefollowing detailed description when taken in connection with theaccompanying illustrations, in which Figure 1 is a diagrammatic sideelevational view, with parts broken away, showing the details of thepresent invention applied to a circular knitting machine.

Figure 2 is a diagrammatic cross-sectional view of the device shown inFigure 1.

Figure 3 is a diagrammatic side elevational view of a flat knittingmachine provided with the present invention.

Figure 4 is a cross-sectional view of the apparatus shown in Figure 3.

Referring to Figures 1- and 2 of the drawing, a plurality of yarns II ispassed to the knitting mechanism I! of a circular knitting apparatus.The knit fabric l5 immediately after it passes from the knittingmechanism is contacted with wick li whereby to apply water to thefabric. The wick I1 is positioned within a chamber i9 whichlmay besupplied with water through conduit 2 Immediately after passing theliquid applying wick, the fabric passes a drying apparatus 23 whichcomprises a narrow slot 25 through which dry air at an elevatedtemperature is blown through the fabric. The air is supplied to thedrying apparatus through conduits 21 and 29.

In the operation of the apparatus shown in Figures 1 and 2, the liquidis fed to the wick I1 and as the fabric moves past the wick, the wateris applied thereto. The wick must apply the water in sumcient amount tosoften the size contained on the yarns of the knit fabric. Theknitfabric then passes adjacent the drier 23 to dry taining a water-solublesize, or a size which can the fabric and thereby resolidify the size onthe Generally, a

- desired manner to apply liquid to the fabric It.

If desired, the liquid may be circulated within the trough 33 by meansof inlet conduit 31 and outlet conduit 33. Immediately after passingfrom the moistening roll 35 the fabric passes over a drying device 23similar to that shown in Figures 1 and 2. r g

The device of Figures 3 and 4 operates in an identical manner with thatshown in Figures 1 and 2.

The water may be applied to the knit goods by any desired liquidapplicating means. It may, for example, be applied by sprinkling,spraying, immersion or the like. Likewise, the fabric may be dried inany known manner for drying fabric. It may be dried by heat convection,conduction or radiation with any known type of drying apparatus.

The following illustrative example clearly shows, in detail, onepreferred method ofpracticing the invention, it being understood thatthe invention is not so limited.

Example Several yarns of 30-denier, 20-filament, 3 -turnpolyhexamethylene adipamide yarn sized with 4% (based on the weight ofthe dried yarn) or a composition consisting of parts of a partiallysaponified polyvinyl acetate'[saponiflcation number 140110 having aviscosity within the range of 400 to 500 seconds (Universal Saybolt) at78 F. in a 14.5% soiution in water] to 2.5 parts of glycerin aresupplied to a conventional B-carrier Wildman full-fashioned hosierymachine adjusted to produce a 51-gauge fabric of 48 courses per inch.The usual yam-moistening devicesare by-passed and the dry yarn feddirectly to the needles by the usual tension devices.

The knitted fabric just leaving the knitting zone is passed in contactwith a wick contacting the fabric one-half inch from the knittingneedles and dipping in water whereby it is wetted. The fabric is thenquickly passed through a drying zone to remove the water within adistance of three inches from the needles. The fabric is maintainedunder sufiicient tension during the wetting and drying to producestitches of the desired shape. v

It was found that when this procedure was used, the knitting stepproceeded remarkably well and free from the difficulties which haveusually accompanied it., It was found too that the knitted fabrics hadexcellent protection against snagging in the subsequent steps and thatedgerolling was reduced to a minimum.

The foregoing example is a specific embodiment of the invention. It willbe understood that many variations are possible within the broad boundsof the invention. Thus, the specific sizing composition is not critical,it being agreed that a sizing composition known to be suitable for nylonyarns will be employed. It is to be noted that this method of sizingobviates the necessity for certain modifying agents, such as boric acid,with sizes that have been found to be suitable for nylon, such aspartially saponiiied polyvinyl resins, which produce poor stitchformation and other undesirable features when used in the conventionalknitting procedure in the absence of such modifiers. By the presentinvention, it may be possible to satisfactorily use sizes which are nototherwise suitable for use in the sizing of nylon yarn. Other sizesgenerally useful in accordance with this invention are, by way ofexample, protein sizes, such as gelatin or casein sizes which have nohardening agent present in them, alginic acids, methyl cellulose,water-soluble glyptal resins, gum tragacanth and other sizes toonumerous to mention. The above-mentioned modified sizes, speciallydeveloped for use in the conventional knitting methods are, of course,notprecluded for use in this invention. It is, in general, desirable,althoughnot necessary, that the sizes used be rather highly plasticisedwith non-aqueous plasticizing agents, for example, glycerin, glycols,polyethylene glycols, esters of polyethylene glycols (e. g., the sebacicacid ester of polyethylene glycol), etc, in order to facilitate goodstitch-formation.

The specific method of moistening the freshly knit fabric and of dryingit are not critical, Any method adaptable to the particular knittingmachine or suitable to the facilities and practices of the knittingplant may be employed. In general, the moistening of the knit fabricshould be carried out before the yarn has passed to exceed about 5inches from the knitting needles, and the drying should be carried outbefore the fabric has progressed to exceed about 5 inches from themoistening apparatus. In the fiat knitting of hosiery fabric with nylonyarn, it i much to be preferred that the sizing composition be softenedby moistening within one inch from the knitting needles since aprolonged delay gives a very lively yarn a chance to roll at the edges.Similarly, and for the same reason, it is greatly preferred that themoisture in the knitted fabric be reduced to below 10%, based on theweight of the dried fabric, within four inches from the needles.

The moistening liquid may contain wetting agents, tints or even resinsor finishing agents.

' If the fabric is knitted with nylon yarn, drying of the moist yarn canbe carried out at a temperature sufiiciently high to cause a setting orpre-boarding of the stocking fabric. For example, the moist knit fabriccan be dried at a temperature in excess of C. whereby the fabric will bepre-set in a manner similar to that disclosed in Miles U. S. Patent No.2,157,119. The yarn should not, of course, be heated to such hightemperatures that the yarn will be softened or degraded. By setting theyarn on the knitting machine in this manner, the knit loops will besubstantially permanently set before they can be distorted.

The invention has been described in terms of nylon yarn and, morespecifically in terms of polyhexamethylene adipamide yarn. It will beunderstood that it is equally useful for other synthetic linearcondensation polymer yarns such as the polyesters, polyanhydrides andpolyethers since these also exhibit a high degree of bending elasticity.The invention, although applicable, is not so important or necessary inthe knitting of cotton, viscose rayon, acetate rayon or silk yarns. Theinvention is applicable to the knitting of monofils whenever it is founddesirable to use a size with the monofils to effect a temporarycementing of the junction points.

specific reference has been made to the manufacture of a stocking fabricin a full-fashion hosiery machine. It will be obvious that many of theprinciples of this invention are equally applicable to the knitting oftubing and to the knitting of seamless hosiery and to other relatedtextile steps.

By virtue of this invention, a knitting procedure is now available whichpermits very rapid knitting with a small degree of interruption and witha production of extremely high quality goods with only ordinarysupervision. Edgerolling is minimized by reason of the fact that the drysized yarn, when knitted into a fabric, does not give a fabric with suchhigh edge-rolling tendency as does an unsized yarn or a wetted sizedyarn; and the wetted sized fabric is dried so quickly that edge-rollingis not permitted to become serious.

Since it is obvious that many changes and modifications can be made inthe above-described details without departing from the nature and spiritof the invention, it is to be understood that the invention is not to belimited to these details except as set forth in the appended claims.

I claim: 1. The method of knitting yarn which comprises knltting a dryyarn containing a water- 'soluble size, applying sufficient water to thefabric to soften the said size and drying the moist fabric after theknit fabric has passed the knitting needles but before the fabric isremoved from the knitting machine.

2. The method of knitting yarn which comprises knitting a dry yarncontaining a watersoluble size, moistening the .fabric with water beforeit has passed to exceed 5 inches from the knitting needles, and dryingthe moistened fabric before it has passed to exceed 5 inches from saidmoistening point.

3. The method of flat knitting full-fashioned hosiery fabric whichcomprises knitting a dry yarn containing a water-soluble size, after theknit fabric has passed the knittingneedles but before it has passed toexceed one inch from said needles, applying sufllcient water to thefabric to soften the said size, andbefore the fabric has passed toexceed four inches from said needles, drying the moist fabric.

4. The method as defined in claim 3 in which the fabric is knit withnylon yarn.

CHARLES R.

